Excellent resistive switching properties of atomic layer-deposited Al2O3/HfO2/Al2O3 trilayer structures for non-volatile memory applications

Abstract

We have demonstrated a flexible resistive random access memory unit with trilayer structure by atomic layer deposition (ALD). The device unit is composed of Al2O3/HfO2/Al2O3-based functional stacks on TiN-coated Si substrate. The cross-sectional HRTEM image and XPS depth profile of Al2O3/HfO2/Al2O3 on TiN-coated Si confirm the existence of interfacial layers between trilayer structures of Al2O3/HfO2/Al2O3 after 600°C post-annealing. The memory units of Pt/Al2O3/HfO2/Al2O3/TiN/Si exhibit a typical bipolar, reliable, and reproducible resistive switching behavior, such as stable resistance ratio (>10) of OFF/ON states, sharp distribution of set and reset voltages, better switching endurance up to 103 cycles, and longer data retention at 85°C over 10 years. The possible switching mechanism of trilayer structure of Al2O3/HfO2/Al2O3 has been proposed. The trilayer structure device units of Al2O3/HfO2/Al2O3 on TiN-coated Si prepared by ALD may be a potential candidate for oxide-based resistive random access memory.

Bipolar Resistive Switching Characteristics of HfO2/TiO2/HfO2 Trilayer-Structure RRAM Devices on Pt and TiN-Coated Substrates Fabricated by Atomic Layer Deposition

“…How to effectively control the distribution of oxygen vacancy filaments is a key issue to finally improving the RS uniformity [20]. Lots of work has shown that usually a nonuniform distribution of oxygen vacancies is beneficial to the RS behaviors, including decreasing the forming voltage, improving the switching stability and endurance ability [1, 14, 20, 26–29]. An initial nonuniform distribution of oxygen vacancies in a storage oxide layer is often obtained by the use of a chemically active electrode with a relatively high oxygen affinity (e.g., Ta, Ti, Al, or TiN) or by deliberately introducing an oxygen vacancy-rich interfacial layer by interface engineering [1, 17, 30].…”

Reproducible and reliable resistive switching behaviors of AlOX/HfOX bilayer structures with Al electrode by atomic layer deposition

“…16 As another approach, numerous studies have focused on manipulation of device structures by incorporating a chemically-active layer, 17,18 by doping, 19,20 and by using bilayer 5,[21][22][23] and trilayer structures. 24 Due to fabrication simplicity to make bilayer RRAM, different structures have been studied, such as ZrO X /HfO X 21 and WO X /NbO X . 25 Inserting an Al layer between electrode and HfO X improves the switching uniformity, possibly by stabilizing the conductive laments.…”

Bipolar resistive switching behaviors of ITO nanowire networks

“…In the metal oxides, the double binding energy of O 1s is very common, which corresponds to the two kinds of chemical states of oxygen ions in material surface, oxygen sufficiency and oxygen deficiency. [25][26][27] The double binding energy presents in sample C (Fig. 5(a)), but there is only one binding energy in sample A (Fig.…”